The present invention relates to an image forming apparatus. More specifically, it relates to an image forming apparatus having a printing device capable of printing some letters on an image-formed sheet.
Japanese Patent Laying-Open No. 53665/1986 discloses an image forming apparatus which has a printing device capable of printing date, name of company, etc. on a sheet of image-formed paper. The printing device essentially consists of an ink-ribbon cassette containing an ink ribbon, and a printing head for pressing the ink ribbon against paper for printing.
The printing quality of the printing device may deteriorate if for example dust or foreign matter becomes affixed to the printing head. Therefore, the printing head must be cleaned regularly.
The printing quality of the letters printed on a sheet by the printing device may also deteriorate, due to heat generated by the fixing unit, which performs its image-fixing process at a high temperature. Since the printing device is located close to the high-temperature fixing device the ink ribbon in the printing device is susceptible to deterioration due to the heat from the fixing unit. The ink ribbon may even melt on occasion.
In maintenance, the printing head should be cleaned, and a printing device having a decayed ink ribbon must be replaced. Since the printing unit is installed as it is within the image forming apparatus, however, it is difficult to clean the printing unit and/or replace it during maintenance.